Safety of deep hypothermia in treating neonatal asphyxia

BACKGROUND: Several studies have demonstrated the efficiency and safety of mild hypothermia (33 degrees C) used for treating moderate encephalopathy. In animal models, deep hypothermia proved to be neuroprotective. OBJECTIVES: To determine the safety of whole-body deep hypothermia between 30 and 33 degrees C in moderate-severe hypoxic-ischemic encephalopathy in newborn term infants. METHODS: Mortality rates, incidence of brain damage detected by magnetic resonance imaging (MRI) and neurological outcomes of 39 term asphyxiated infants were retrospectively compared. A first group of patients (control group C) was treated with routine standard methods, a second group (MH) was treated with mild whole-body hypothermia (32-34 degrees C) and a third group (DH) was treated with deep whole-body hypothermia (30-33 degrees C), for 72 h. Mean arterial pH, basic excess (BE) and lactic acid in the blood were measured. Laboratory and clinical side effects of hypothermia were investigated. A conventional brain MRI was performed after the second week of life. Results: 39 term asphyxiated newborns were enrolled in the study: 11 in group C, 10 in group MH, and 18 in group DH. During the first 72 h, disseminated intravascular coagulation was recorded in 2 cases (18%) in group C, pulmonary hypertension in 2 patients (20%) in group MH, and pneumonia in 3 cases (16%) in group DH. Severe cerebral lesions and poor neurological outcome were observed in 4 cases (36%) in group C, 1 case (10%) in group MH, and 1 case (5%) in group DH. A statistically significant difference in brain damage and major clinical neurological abnormalities was observed between group C and groups MH and DH, whereas no differences were demonstrated between asphyxiated infants treated with mild or deep hypothermia. CONCLUSIONS: The results support the safety of deep hypothermia. Further studies are needed to confirm these results and the neuroprotective effect of this approach.